Research On Quality Impovement Of LCD Monitor Assembly Facotory By Six Sigma Method

With different customers, multiple types of products introduced in MonitorAssembly Factory, related and unexpected quality issues appeared as well. Based onthe definition of quality levels of products, the management of factory pays moreattention to those Ctritical issues and Major issues, for example, products on fire,hi-pot test, life cycle test, function problems etc. And less attention to those Minorissues, for example, cosmetic issues.The cosmetic defects take a long-term top3defects position in recent threemonths. Although factory engineering departments take some quality improvementaction to those “single” cases, the problems still exist. To permanently settle thisquality issue, I, as factory QA department head, hold and set up a special6sigma team,lead the team to take the cosmetic problem study to reduce defect rate as the projectsubject.Firstly, in Define phase, after team setting up, raw data and information ofmechanical defects will be categorized and collected. From the Analyze of theproduction of all customers, we decided to choose H customer products as the studysubject. Then initially, the improvement subject is divided into two directions whichone is focused in Monitor facroty, the other is focused in MMP factory.Secondly, in Measure phase, after the Analyze of process map of MMP andMonitor assembly factory, invisible factory, Value Added and Not Value Added arefound out. MSA is performed to verify the main judgement system of cosmeticstations is qualified, if not, related corrective actions will be taken to make sure themeasurement system are fulfilled.Thirdly, in Analyze phase, after testifying related factors of all those importantfactors by box plot, ANOVA etc Analyze tools, to clarify whether factors can makeobvious effect to the subject. And after the Analyze, two factors, roasting temperatureand roasting time are eliminated. Then the regression Analyze result shows that theremaining factors are the main factors.Forthly, in Improve phase, excluding the factors which already been takencorrective actions, DOE plan is carried out for the line speed, painting thickness, andcool time. Line speed DOE plan is single factor,5levels, painting thickness and cooltime are2factors,2levels. Through Minitab tool, we find out the optimized result. Fifthly, in Control phase, main task to summarize all the corrective actions frompast phases, and make control plan, verify SPC and MSA system, then to standardizerelated documents. After three months improvement verification, the6sigma teamcan transfer the continuous improvement task to factory related departments.